Biological interaction
Interactions can be direct when physical contact is established or indirect, through intermediaries such as shared resources, territories, ecological services, metabolic waste, toxins or growth inhibitors.
Several recent studies have suggested non-trophic species interactions such as habitat modification and mutualisms can be important determinants of food web structures.
Close and long-term interactions are described as symbiosis;[a] symbioses that are mutually beneficial are called mutualistic.
[2][3][4] The term symbiosis was subject to a century-long debate about whether it should specifically denote mutualism, as in lichens or in parasites that benefit themselves.
[citation needed] Short-term interactions, including predation and pollination, are extremely important in ecology and evolution.
Many predatory animals, both vertebrate and invertebrate, have sharp claws or jaws to grip, kill, and cut up their prey.
Predation has a powerful selective effect on prey, causing them to develop antipredator adaptations such as warning coloration, alarm calls and other signals, camouflage and defensive spines and chemicals.
[11] The partners have coevolved through geological time; in the case of insects and flowering plants, the coevolution has continued for over 100 million years.
Pollinator insects like bees are adapted to detect flowers by colour, pattern, and scent, to collect and transport pollen (such as with bristles shaped to form pollen baskets on their hind legs), and to collect and process nectar (in the case of honey bees, making and storing honey).
Examples include cleaning symbiosis, gut flora, Müllerian mimicry, and nitrogen fixation by bacteria in the root nodules of legumes.
[21] Neutralism (a term introduced by Eugene Odum)[22] describes the relationship between two species that interact but do not affect each other.
Examples of true neutralism are virtually impossible to prove; the term is in practice used to describe situations where interactions are negligible or insignificant.
A classic example of amensalism is the microbial production of antibiotics that can inhibit or kill other, susceptible microorganisms.
Amensalism is often used to describe strongly asymmetrical competitive interactions, such as has been observed between the Spanish ibex and weevils of the genus Timarcha which feed upon the same type of shrub.
[36][37][41] However these studies include only a limited number of coastal systems, and it remains unclear to what extent these findings can be generalized.
